Two types of grafting: One is canopy change, top work a tree to graft a know or preferred variety on a seedling or change a variety. The other is grafting on to a small seedling.For top working, depending on the size of the tree it needs to be decapitated (like I show on my videos) in order to get water shoots to grow to graft on. The best months to do that are later July to early September so the trees will be ready to graft in December to FebruaryFor grafting on to seedlings you can plant the seeds from July to August to have good size seedling to graft in December to February. Remember good healty seedlings and strong water shoots plus scion ready to flower is the best conbination. . I prefer bud wood in the 511 to 512 category see pictures here: http://www.myavocadotrees.com/stages-of-avocado-flowering-using-the-bbch-scale.html